Simd sign operation

ABSTRACT

Method, apparatus, and program means for nonlinear filtering and deblocking applications utilizing SIMD sign and absolute value operations. The method of one embodiment comprises receiving first data for a first block and second data for a second block. The first data and said second data are comprised of a plurality of rows and columns of pixel data. A block boundary between the first block and the second block is characterized. A correction factor for a deblocking algorithm is calculated with a first instruction for a sign operation that multiplies and with a second instruction for an absolute value operation. Data for pixels located along said block boundary between the first and second block are corrected.

CROSS REFERENCE TO OTHER APPLICATIONS

This patent application is a Continuation of U.S. patent applicationSer. No. 15/066,468, filed Mar. 10, 2016 which is a Continuation of U.S.patent application Ser. No. 13/844,034, filed Mar. 15, 2013, now U.S.Pat. No. 9,329,862, issued on May 3, 2016, which is a Continuation ofU.S. patent application Ser. No. 13/602,502, filed Sep. 4, 2012, nowU.S. Pat. No. 8,510,363, issued on Aug. 13, 2013, which is aContinuation of U.S. patent application Ser. No. 12/231,966, filed Sep.8, 2008, now U.S. Pat. No. 8,271,565, issued on Sep. 18, 2012, which isa Division of U.S. patent application Ser. No. 10/610,665, filed Jun.30, 2003, now U.S. Pat. No. 7,424,501, issued on Sep. 9, 2008. Thespecification of this application discloses similar subject matter asU.S. patent application Ser. No. 10/610,929, entitled, “A Method,Apparatus, And Instruction For Performing A Sign Operation ThatMultiplies” filed Jun. 30, 2003, now U.S. Pat. No. 7,539,714. U.S.patent application Ser. No. 10/610,665 is hereby incorporated byreference.

FIELD OF THE INVENTION

The present disclosure pertains to the field of processing apparatusesand associated software and software sequences that perform mathematicaloperations.

DESCRIPTION OF RELATED ART

Computer systems have become increasingly pervasive in our society. Theprocessing capabilities of computers have increased the efficiency andproductivity of workers in a wide spectrum of professions. As the costsof purchasing and owning a computer continues to drop, more and moreconsumers have been able to take advantage of newer and faster machines.Furthermore, many people enjoy the use of notebook computers because ofthe freedom. Mobile computers allow users to easily transport their dataand work with them as they leave the office or travel. This scenario isquite familiar with marketing staff, corporate executives, and evenstudents.

As processor technology advances, newer software code is also beinggenerated to run on machines with these processors. Users generallyexpect and demand higher performance from their computers regardless ofthe type of software being used. One such issue can arise from the kindsof instructions and operations that are actually being performed withinthe processor. Certain types of operations require more time to completebased on the complexity of the operations and/or type of circuitryneeded. This provides an opportunity to optimize the way certain complexoperations are executed inside the processor.

Media applications have been driving microprocessor development for morethan a decade. In fact, most computing upgrades in recent years havebeen driven by media applications. These upgrades have predominantlyoccurred within consumer segments, although significant advances havealso been seen in enterprise segments for entertainment enhancededucation and communication purposes. Nevertheless, future mediaapplications will require even higher computational requirements. As aresult, tomorrow's personal computing experience will be even richer inaudio-visual effects, as well as being easier to use, and moreimportantly, computing will merge with communications.

Accordingly, the display of images, as well as playback of audio andvideo data, which is collectively referred to as content, have becomeincreasingly popular applications for current computing devices.Filtering and convolution operations are some of the most commonoperations performed on content data, such as image audio and videodata. Such operations are computationally intensive, but offer a highlevel of data parallelism that can be exploited through an efficientimplementation using various data storage devices, such as for example,single instruction multiple data (SIMD) registers. A number of currentarchitectures also require unnecessary data type changes which minimizesinstruction throughput and significantly increases the number of clockcycles required to order data for arithmetic operations.

Various prior art sign related instructions, such as a signuminstruction. determine the sign of a binary number. However, thecapabilities of these prior art signum instructions are limited inusefulness, especially in applications where the further processing ofthe signum results is needed because these results are intermediateresults of larger algorithms. By requiring additional instructions toachieve the desired results, additional costs were incurred in terms ofprocessing resources and pipeline slots.

BRIEF DESCRIPTION OF THE FIGURES

The present invention is illustrated by way of example and notlimitation in the Figures of the accompanying drawings:

FIG. 1A is a block diagram of a computer system formed with a processorthat includes execution units to execute an instruction for a signoperation that multiplies in accordance with one embodiment of thepresent invention;

FIG. 1B is a block diagram of another exemplary computer system inaccordance with an alternative embodiment of the present invention;

FIG. 1C is a block diagram of yet another exemplary computer system inaccordance with another alternative embodiment of the present invention;

FIG. 2 is a block diagram of the micro-architecture for a processor ofone embodiment that includes logic circuits to perform a sign operationthat multiplies in accordance with the present invention;

FIG. 3A illustrates various packed data type representations inmultimedia registers according to one embodiment of the presentinvention;

FIG. 3B illustrates packed data-types in accordance with an alternativeembodiment;

FIG. 3C illustrates various signed and unsigned packed data typerepresentations in multimedia registers according to one embodiment ofthe present invention;

FIG. 3D illustrates one embodiment of an operation encoding (opcode)format;

FIG. 3E illustrates an alternative operation encoding (opcode) format;

FIG. 3F illustrates yet another alternative operation encoding format;

FIG. 4 is a block diagram of one embodiment of logic to perform a signoperation on packed data operands in accordance with the presentinvention;

FIG. 5 illustrates the operation of a sign operation that multiplies ondata elements in accordance with one embodiment of the presentinvention;

FIG. 6A is a block diagram of one embodiment of a circuit for performinga sign operation in accordance with the present invention;

FIG. 6B is a block diagram of another embodiment of a circuit forperforming a sign operation in accordance with the present invention;

FIG. 7 illustrates the operation of a packed sign instruction on aplurality data elements in accordance with one embodiment of the presentinvention;

FIG. 8A is a flow chart illustrating one embodiment of a method toperform a sign operation;

FIG. 8B is a flow chart illustrating another embodiment of a method toperform a sign operation;

FIG. 9 is a block diagram of one embodiment of logic to perform anabsolute value operation on a packed data operand;

FIG. 10 illustrates the operation of a deblocking algorithm using SIMDinstructions in accordance with the present invention; and

FIG. 11 is a flow chart illustrating one embodiment of a method toperform a deblocking algorithm using SIMD instructions.

DETAILED DESCRIPTION

The following description describes embodiments of nonlinear filteringand deblocking applications utilizing SIMD sign and absolute valueoperations. In the following description, numerous specific details suchas processor types, micro-architectural conditions, events, enablementmechanisms, and the like are set forth in order to provide a morethorough understanding of the present invention. It will be appreciated,however, by one skilled in the art that the invention may be practicedwithout such specific details. Additionally, some well known structures,circuits, and the like have not been shown in detail to avoidunnecessarily obscuring the present invention.

Although the following embodiments are described with reference to aprocessor, other embodiments are applicable to other types of integratedcircuits and logic devices. The same techniques and teachings of thepresent invention can easily be applied to other types of circuits orsemiconductor devices that can benefit from higher pipeline throughputand improved performance. The teachings of the present invention areapplicable to any processor or machine that performs data manipulations.However, the present invention is not limited to processors or machinesthat perform 256 bit, 128 bit, 64 bit, 32 bit, or 16 bit data operationsand can be applied to any processor and machine in which manipulation ofpacked data is needed.

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. One of ordinary skill in theart, however, will appreciate that these specific details are notnecessary in order to practice the present invention. In otherinstances, well known electrical structures and circuits have not beenset forth in particular detail in order to not necessarily obscure thepresent invention. In addition, the following description providesexamples, and the accompanying drawings show various examples for thepurposes of illustration. However, these examples should not beconstrued in a limiting sense as they are merely intended to provideexamples of the present invention rather than to provide an exhaustivelist of all possible implementations of the present invention.

Although the below examples describe instruction handling anddistribution in the context of execution units and logic circuits, otherembodiments of the present invention can be accomplished by way ofsoftware. In one embodiment, the methods of the present invention areembodied in machine-executable instructions. The instructions can beused to cause a general-purpose or special-purpose processor that isprogrammed with the instructions to perform the steps of the presentinvention. The present invention may be provided as a computer programproduct or software which may include a machine or computer-readablemedium having stored thereon instructions which may be used to program acomputer (or other electronic devices) to perform a process according tothe present invention. Alternatively, the steps of the present inventionmight be performed by specific hardware components that containhardwired logic for performing the steps, or by any combination ofprogrammed computer components and custom hardware components. Suchsoftware can be stored within a memory in the system. Similarly, thecode can be distributed via a network or by way of other computerreadable media.

Thus a machine-readable medium may include any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer), but is not limited to, floppy diskettes, optical disks,Compact Disc, Read-Only Memory (CD-ROMs), and magneto-optical disks,Read-Only Memory (ROMs), Random Access Memory (RAM), ErasableProgrammable Read-Only Memory (EPROM), Electrically ErasableProgrammable Read-Only Memory (EEPROM), magnetic or optical cards, flashmemory, a transmission over the Internet, electrical, optical,acoustical or other forms of propagated signals (e.g., carrier waves,infrared signals, digital signals, etc.) or the like. Accordingly, thecomputer-readable medium includes any type of media/machine-readablemedium suitable for storing or transmitting electronic instructions orinformation in a form readable by a machine (e.g., a computer).Moreover, the present invention may also be downloaded as a computerprogram product. As such, the program may be transferred from a remotecomputer (e.g., a server) to a requesting computer (e.g., a client). Thetransfer of the program may be by way of electrical, optical,acoustical, or other forms of data signals embodied in a carrier wave orother propagation medium via a communication link (e.g., a modem,network connection or the like).

A design may go through various stages, from creation to simulation tofabrication. Data representing a design may represent the design in anumber of manners. First, as is useful in simulations, the hardware maybe represented using a hardware description language or anotherfunctional description language Additionally, a circuit level model withlogic and/or transistor gates may be produced at some stages of thedesign process. Furthermore, most designs, at some stage, reach a levelof data representing the physical placement of various devices in thehardware model. In the case where conventional semiconductor fabricationtechniques are used, the data representing the hardware model may be thedata specifying the presence or absence of various features on differentmask layers for masks used to produce the integrated circuit. In anyrepresentation of the design, the data may be stored in any form of amachine readable medium. An optical or electrical wave modulated orotherwise generated to transmit such information, a memory, or amagnetic or optical storage such as a disc may be the machine readablemedium. Any of these mediums may “carry” or “indicate” the design orsoftware information. When an electrical carrier wave indicating orcarrying the code or design is transmitted, to the extent that copying,buffering, or re-transmission of the electrical signal is performed, anew copy is made. Thus, a communication provider or a network providermay make copies of an article (a carrier wave) embodying techniques ofthe present invention.

In modern processors, a number of different execution units are used toprocess and execute a variety of code and instructions. Not allinstructions are created equal as some are quicker to complete whileothers can take an enormous number of clock cycles. The faster thethroughput of instructions, the better the overall performance of theprocessor. Thus it would be advantageous to have as many instructionsexecute as fast as possible. However, there are certain instructionsthat have greater complexity and require more in terms of execution timeand processor resources. For example, there are floating pointinstructions, load/store operations, data moves, etc.

As more and more computer systems are used in internet and multimediaapplications, additional processor support has been introduced overtime. For instance, Single Instruction, Multiple Data (SIMD)integer/floating point instructions and Streaming SIMD Extensions (SSE)are instructions that reduce the overall number of instructions requiredto execute a particular program task, which in turn can reduce the powerconsumption. These instructions can speed up software performance byoperating on multiple data elements in parallel. As a result,performance gains can be achieved in a wide range of applicationsincluding video, speech, and image/photo processing. The implementationof SIMD instructions in microprocessors and similar types of logiccircuit usually involve a number of issues. Furthermore, the complexityof SIMD operations often leads to a need for additional circuitry inorder to correctly process and manipulate the data.

Presently a SIMD sign instruction that multiplies is not available. Noris there a SIMD instruction for absolute value operations. Without thepresence of a sign operation that multiplies, a large number ofinstructions and data registers are needed to accomplish the sameresults in applications such as audio/video compression, processing, andmanipulation. Thus, a sign instructions in accordance to the presentinvention can reduce code overhead and resource requirements.Embodiments of the present invention provide a way to implement a signoperation as an algorithm that makes use of SIMD related hardware. Someembodiments also provide ways to implement an absolute value operation.Presently, it is somewhat difficult and tedious to operate on data in aSIMD register. Some algorithms require more instructions to arrange datafor arithmetic operations than the actual number of instructions toexecute those operations. By implementing embodiments of a signoperation that multiplies in accordance with the present invention, thenumber of instructions needed to achieve sign processing can bedrastically reduced.

Embodiments of the present invention involve an instruction forimplementing a variation of a signum operation. A signum operationdetermines whether a given number is positive, negative, or zero. Duringa signum operation, the function evaluates a number as: for x>0,signum(x)=1; for x=0, signum(x)=0; and for x<0, signum(x)=−1. However,in multimedia applications, the multiplication of a data value by thesign of another value is often needed during various algorithms. A signoperation that multiplies can avoid having to do many separateoperations. Embodiments of the present sign operation provides morefunctionality than the signum and also includes the multiplication.

A sign instruction in accordance to the present invention computes theoperation: DEST=SRC1×SIGNUM(SRC2). If SRC2 is positive, the signum ofSRC2 will provide a value of ‘+1’. If SRC2 is equal to zero, the resultof the signum of SRC2 is zero. If SRC2 is negative, then the signum ofSRC2 is ‘−1’. The sign operation that multiplies as in embodiment of thepresent invention takes the signum of a second data element andmultiplies the signum result with the value of a first data element toobtain a resultant product. The sign operation of one embodiment asapplied to an individual data element can be represented as:

if SOURCE2<0, then DEST=SOURCE1×‘−1’;

else if SOURCE2==0, then DEST=0;

else if SOURCE2>0, then DEST=SOURCE1×‘+1’.

For a packed data operand, this flow can be applied to each data elementposition.

Furthermore, one embodiment of a sign operation that multiplies can alsomimic the signum operation by using the value ‘1’ as the first sourceelement and the value of interest as the second source element in a signoperation. Because the sign operation of this embodiment causes amultiplication of the first source element with one of ‘+1’, ‘0’, or‘−1’ based on the sign value of the second element, signum can bereplicated here. Similarly, embodiments of the sign operation of thisinvention can also perform absolute value operations by setting firstsource element to the sign operation equal to the second source element.This is achievable because the source value will essentially bemultiplied by its own sign, thus making the resultant value a ‘0’ orpositive.

FIG. 1A is a block diagram of an exemplary computer system formed with aprocessor that includes execution units to execute an instruction for asign operation that multiplies in accordance with one embodiment of thepresent invention. System 100 includes a component, such as a processor102 to employ execution units including logic to perform algorithms forprocess data, in accordance with the present invention, such as in theembodiment described herein. System 100 is representative of processingsystems based on the PENTIUM® III, PENTIUM® 4, Xeon™, Itanium®, XScale™and/or StrongARM™ microprocessors available from Intel Corporation ofSanta Clara, Calif., although other systems (including PCs having othermicroprocessors, engineering workstations, set-top boxes and the like)may also be used. In one embodiment, sample system 100 may execute aversion of the WINDOWS™ operating system available from MicrosoftCorporation of Redmond, Wash., although other operating systems (UNIXand Linux for example), embedded software, and/or graphical userinterfaces, may also be used. Thus, the present invention is not limitedto any specific combination of hardware circuitry and software.

The present enhancement is not limited to computer systems. Alternativeembodiments of the present invention can be used in other devices suchas handheld devices and embedded applications. Some examples of handhelddevices include cellular phones, Internet Protocol devices, digitalcameras, personal digital assistants (PDAs), and handheld PCs. Embeddedapplications can include a micro controller, a digital signal processor(DSP), system on a chip, network computers (NetPC), set-top boxes,network hubs, wide area network (WAN) switches, or any other system thatperforms sign and/or absolute value operations on operands. Furthermore,some architectures have been implemented to enable instructions tooperate on several data simultaneously to improve the efficiency ofmultimedia applications. As the type and volume of data increases,computers and their processors have to be enhanced to manipulate data inmore efficient methods.

FIG. 1A is a block diagram of a computer system 100 formed with aprocessor 102 that includes one or more execution units 108 to performan algorithm to extract the sign of a data element from one operand andmultiply that sign with another data element in accordance with thepresent invention. The present embodiment is described in the context ofa single processor desktop or server system, but alternative embodimentscan be included in a multiprocessor system. System 100 is an example ofa hub architecture. The computer system 100 includes a processor 102 toprocess data signals. The processor 102 can be a complex instruction setcomputer (CISC) microprocessor, a reduced instruction set computing(RISC) microprocessor, a very long instruction word (VLIW)microprocessor, a processor implementing a combination of instructionsets, or any other processor device, such as a digital signal processor,for example. The processor 102 is coupled to a processor bus 110 thatcan transmit data signals between the processor 102 and other componentsin the system 100. The elements of system 100 perform their conventionalfunctions that are well known to those familiar with the art.

In one embodiment, the processor 102 includes a Level 1 (L1) internalcache memory 104. Depending on the architecture, the processor 102 canhave a single internal cache or multiple levels of internal cache.Alternatively, in another embodiment, the cache memory can resideexternal to the processor 102. Other embodiments can also include acombination of both internal and external caches depending on theparticular implementation and needs. Register file 106 can storedifferent types of data in various registers including integerregisters, floating point registers, status registers, and instructionpointer register.

Execution unit 108, including logic to perform integer and floatingpoint operations, also resides in the processor 102. The processor 102also includes a microcode (ucode) ROM that stores microcode for certainmacroinstructions. For this embodiment, execution unit 108 includeslogic to handle a packed instruction set 109. In one embodiment, thepacked instruction set 109 includes a packed sign instruction formodifying the sign value of data. By including the packed instructionset 109 in the instruction set of a general-purpose processor 102, alongwith associated circuitry to execute the instructions, the operationsused by many multimedia applications may be performed using packed datain a general-purpose processor 102. Thus, many multimedia applicationscan be accelerated and executed more efficiently by using the full widthof a processor's data bus for performing operations on packed data. Thiscan eliminate the need to transfer smaller units of data across theprocessor's data bus to perform one or more operations one data elementat a time.

Alternate embodiments of an execution unit 108 can also be used in microcontrollers, embedded processors, graphics devices, DSPs, and othertypes of logic circuits. System 100 includes a memory 120. Memory 120can be a dynamic random access memory (DRAM) device, a static randomaccess memory (SRAM) device, flash memory device, or other memorydevice. Memory 120 can store instructions and/or data represented bydata signals that can be executed by the processor 102.

A system logic chip 116 is coupled to the processor bus 110 and memory120. The system logic chip 116 in the illustrated embodiment is a memorycontroller hub (MCH). The processor 102 can communicate to the MCH 116via a processor bus 110. The MCH 116 provides a high bandwidth memorypath 118 to memory 120 for instruction and data storage and for storageof graphics commands, data and textures. The MCH 116 is to direct datasignals between the processor 102, memory 120, and other components inthe system 100 and to bridge the data signals between processor bus 110,memory 120, and system I/O 122. In some embodiments, the system logicchip 116 can provide a graphics port for coupling to a graphicscontroller 112. The MCH 116 is coupled to memory 120 through a memoryinterface 118. The graphics card 112 is coupled to the MCH 116 throughan Accelerated Graphics Port (AGP) interconnect 114.

System 100 uses a proprietary hub interface bus 122 to couple the MCH116 to the I/O controller hub (ICH) 130. The ICH 130 provides directconnections to some I/O devices via a local I/O bus. The local I/O busis a high-speed I/O bus for connecting peripherals to the memory 120,chipset, and processor 102. Some examples are the audio controller,firmware hub (flash BIOS) 128, wireless transceiver 126, data storage124, legacy I/O controller containing user input and keyboardinterfaces, a serial expansion port such as Universal Serial Bus (USB),and a network controller 134. The data storage device 124 can comprise ahard disk drive, a floppy disk drive, a CD-ROM device, a flash memorydevice, or other mass storage device.

For another embodiment of a system, an execution unit to execute analgorithm with a sign instruction can be used with a system on a chip.One embodiment of a system on a chip comprises of a processor and amemory. The memory for one such system is a flash memory. The flashmemory can be located on the same die as the processor and other systemcomponents. Additionally, other logic blocks such as a memory controlleror graphics controller can also be located on a system on a chip.

FIG. 1B illustrates an alternative embodiment of a data processingsystem 140 which implements the principles of the present invention. Oneembodiment of data processing system 140 is an Intel® Personal InternetClient Architecture (Intel® PCA) applications processors with IntelXScale™ technology (as described on the world-wide web atdeveloper.intel.com). It will be readily appreciated by one of skill inthe art that the embodiments described herein can be used withalternative processing systems without departure from the scope of theinvention.

Computer system 140 comprises a processing core 159 capable ofperforming SIMD operations including a sign and absolute value. For oneembodiment, processing core 159 represents a processing unit of any typeof architecture, including but not limited to a CISC, a RISC or a VLIWtype architecture. Processing core 159 may also be suitable formanufacture in one or more process technologies and by being representedon a machine readable media in sufficient detail, may be suitable tofacilitate said manufacture.

Processing core 159 comprises an execution unit 142, a set of registerfile(s) 145, and a decoder 144. Processing core 159 also includesadditional circuitry (not shown) which is not necessary to theunderstanding of the present invention. Execution unit 142 is used forexecuting instructions received by processing core 159. In addition torecognizing typical processor instructions, execution unit 142 canrecognize instructions in packed instruction set 143 for performingoperations on packed data formats. Packed instruction set 143 includesinstructions for supporting sign and absolute value operations, and mayalso include other packed instructions. Execution unit 142 is coupled toregister file 145 by an internal bus. Register file 145 represents astorage area on processing core 159 for storing information, includingdata. As previously mentioned, it is understood that the storage areaused for storing the packed data is not critical. Execution unit 142 iscoupled to decoder 144. Decoder 144 is used for decoding instructionsreceived by processing core 159 into control signals and/or microcodeentry points. In response to these control signals and/or microcodeentry points, execution unit 142 performs the appropriate operations.

Processing core 159 is coupled with bus 141 for communicating withvarious other system devices, which may include but are not limited to,for example, synchronous dynamic random access memory (SDRAM) control146, static random access memory (SRAM) control 147, burst flash memoryinterface 148, personal computer memory card international association(PCMCIA)/compact flash (CF) card control 149, liquid crystal display(LCD) control 150, direct memory access (DMA) controller 151, andalternative bus master interface 152. In one embodiment, data processingsystem 140 may also comprise an I/O bridge 154 for communicating withvarious I/O devices via an I/O bus 153. Such I/O devices may include butare not limited to, for example, universal asynchronousreceiver/transmitter (UART) 155, universal serial bus (USB) 156,Bluetooth wireless UART 157 and I/O expansion interface 158.

One embodiment of data processing system 140 provides for mobile,network and/or wireless communications and a processing core 159 capableof performing SIMD operations including a sign or absolute valueoperation. Processing core 159 may be programmed with various audio,video, imaging and communications algorithms including discretetransformations such as a Walsh-Hadamard transform, a fast Fouriertransform (FFT), a discrete cosine transform (DCT), and their respectiveinverse transforms; compression/decompression techniques such as colorspace transformation, video encode motion estimation or video decodemotion compensation; and modulation/demodulation (MODEM) functions suchas pulse coded modulation (PCM).

FIG. 1C illustrates yet alternative embodiments of a data processingsystem capable of performing SIMD sign or absolute value operations. Inaccordance with one alternative embodiment, data processing system 160may include a main processor 166, a SIMD coprocessor 161, a cache memory167, and an input/output system 168. The input/output system 168 mayoptionally be coupled to a wireless interface 169. SIMD coprocessor 161is capable of performing SIMD operations including sign or absolutevalue. Processing core 170 may be suitable for manufacture in one ormore process technologies and by being represented on a machine readablemedia in sufficient detail, may be suitable to facilitate themanufacture of all or part of data processing system 160 includingprocessing core 170.

For one embodiment, SIMD coprocessor 161 comprises an execution unit 162and a set of register file(s) 164. One embodiment of main processor 165comprises a decoder 165 to recognize instructions of instruction set 163including SIMD sign and absolute value instructions for execution byexecution unit 162. For alternative embodiments, SIMD coprocessor 161also comprises at least part of decoder 165B to decode instructions ofinstruction set 163. Processing core 170 also includes additionalcircuitry (not shown) which is not necessary to the understanding of thepresent invention.

In operation, the main processor 166 executes a stream of dataprocessing instructions that control data processing operations of ageneral type including interactions with the cache memory 167, and theinput/output system 168. Embedded within the stream of data processinginstructions are SIMD coprocessor instructions. The decoder 165 of mainprocessor 166 recognizes these SIMD coprocessor instructions as being ofa type that should be executed by an attached SIMD coprocessor 161.Accordingly, the main processor 166 issues these SIMD coprocessorinstructions (or control signals representing SIMD coprocessorinstructions) on the coprocessor bus 166 where from they are received byany attached SIMD coprocessors. In this case, the SIMD coprocessor 161will accept and execute any received SIMD coprocessor instructionsintended for it.

Data may be received via wireless interface 169 for processing by theSIMD coprocessor instructions. For one example, voice communication maybe received in the form of a digital signal, which may be processed bythe SIMD coprocessor instructions to regenerate digital audio samplesrepresentative of the voice communications. For another example,compressed audio and/or video may be received in the form of a digitalbit stream, which may be processed by the SIMD coprocessor instructionsto regenerate digital audio samples and/or motion video frames. For oneembodiment of processing core 170, main processor 166, and a SIMDcoprocessor 161 are integrated into a single processing core 170comprising an execution unit 162, a set of register file(s) 164, and adecoder 165 to recognize instructions of instruction set 163 includingSIMD sign and absolute value instructions.

FIG. 2 is a block diagram of the micro-architecture for a processor 200of one embodiment that includes logic circuits to perform a signoperation that multiplies in accordance with the present invention. Thesign operation may also be referred to as a packed sign operation andpacked sign instruction as in the discussion above. For one embodimentof the sign instruction, the instruction can multiply a first dataelement with the sign value of a second data element. That instructioncan also be referred to as PSIGN or packed sign. In this embodiment, thesign instruction can also be implemented to operate on data elementshaving sizes of byte, word, doubleword, quadword, etc. The in-orderfront end 201 is the part of the processor 200 that fetches themacro-instructions to be executed and prepares them to be used later inthe processor pipeline. The front end 201 of this embodiment includesseveral units. The instruction prefetcher 226 fetches macro-instructionsfrom memory and feeds them to an instruction decoder 228 which in turndecodes them into primitives called micro-instructions ormicro-operations (also called micro op or uops) that the machine knowhow to execute. The trace cache 230 takes decoded uops and assemblesthem into program ordered sequences or traces in the uop queue 234 forexecution. When the trace cache 230 encounters a complexmacro-instruction, the microcode ROM 232 provides the uops needed tocomplete the operation.

Many macro-instructions are converted into a single micro-op, and othersneed several micro-ops to complete the full operation. In thisembodiment, if more than four micro-ops are needed to complete amacro-instruction, the decoder 228 accesses the microcode ROM 232 to dothe macro-instruction. For one embodiment, a packed sign instruction canbe decoded into a small number of micro ops for processing at theinstruction decoder 228. In another embodiment, an instruction for apacked sign algorithm can be stored within the microcode ROM 232 shoulda number of micro-ops be needed to accomplish the operation. The tracecache 230 refers to a entry point programmable logic array (PLA) todetermine a correct micro-instruction pointer for reading the micro-codesequences for the sign or absolute value algorithms in the micro-codeROM 232. After the microcode ROM 232 finishes sequencing micro-ops forthe current macro-instruction, the front end 201 of the machine resumesfetching micro-ops from the trace cache 230.

Some SIMD and other multimedia types of instructions are consideredcomplex instructions. Most floating point related instructions are alsocomplex instructions. As such, when the instruction decoder 228encounters a complex macro-instruction, the microcode ROM 232 isaccessed at the appropriate location to retrieve the microcode sequencefor that macro-instruction. The various micro-ops needed for performingthat macro-instruction are communicated to the out-of-order executionengine 203 for execution at the appropriate integer and floating pointexecution units.

The out-of-order execution engine 203 is where the micro-instructionsare prepared for execution. The out-of-order execution logic has anumber of buffers to smooth out and re-order the flow ofmicro-instructions to optimize performance as they go down the pipelineand get scheduled for execution. The allocator logic allocates themachine buffers and resources that each uop needs in order to execute.The register renaming logic renames logic registers onto entries in aregister file. The allocator also allocates an entry for each uop in oneof the two uop queues, one for memory operations and one for non-memoryoperations, in front of the instruction schedulers: memory scheduler,fast scheduler 202, slow/general floating point scheduler 204, andsimple floating point scheduler 206. The uop schedulers 202, 204, 206,determine when a uop is ready to execute based on the readiness of theirdependent input register operand sources and the availability of theexecution resources the uops need to complete their operation. The fastscheduler 202 of this embodiment can schedule on each half of the mainclock cycle while the other schedulers can only schedule once per mainprocessor clock cycle. The schedulers arbitrate for the dispatch portsto schedule uops for execution.

Register files 208, 210, sit between the schedulers 202, 204, 206, andthe execution units 212, 214, 216, 218, 220, 222, 224 in the executionblock 211. There is a separate register file 208, 210, for integer andfloating point operations, respectively. Each register file 208, 210, ofthis embodiment also includes a bypass network that can bypass orforward just completed results that have not yet been written into theregister file to new dependent uops. The integer register file 208 andthe floating point register file 210 are also capable of communicatingdata with the other. For one embodiment, the integer register file 208is split into two separate register files, one register file for the loworder 32 bits of data and a second register file for the high order 32bits of data. The floating point register file 210 of one embodiment has128 bit wide entries because floating point instructions typically haveoperands from 64 to 128 bits in width.

The execution block 211 contains the execution units 212, 214, 216, 218,220, 222, 224, where the instructions are actually executed. Thissection includes the register files 208, 210, that store the integer andfloating point data operand values that the micro-instructions need toexecute. The processor 200 of this embodiment is comprised of a numberof execution units: address generation unit (AGU) 212, AGU 214, fast ALU216, fast ALU 218, slow ALU 220, floating point ALU 222, floating pointmove unit 224. For this embodiment, the floating point execution blocks222, 224, execute floating point, MMX, SIMD, and SSE operations. Thefloating point ALU 222 of this embodiment includes a 64 bit by 64 bitfloating point divider to execute divide, square root, and remaindermicro-ops. For embodiments of the present invention, any act involving afloating point value occurs with the floating point hardware. Forexample, conversions between integer format and floating point formatinvolve a floating point register file. Similarly, a floating pointdivide operation happens at a floating point divider. On the other hand,non-floating point numbers and integer type are handled with integerhardware resources. The simple, very frequent ALU operations go to thehigh-speed ALU execution units 216, 218. The fast ALUs 216, 218, of thisembodiment can execute fast operations with an effective latency of halfa clock cycle. For one embodiment, most complex integer operations go tothe slow ALU 220 as the slow ALU 220 includes integer execution hardwarefor long latency type of operations, such as a multiplier, shifts, flaglogic, and branch processing. Memory load/store operations are executedby the AGUs 212, 214. For this embodiment, the integer ALUs 216, 218,220, are described in the context of performing integer operations on 64bit data operands. In alternative embodiments, the ALUs 216, 218, 220,can be implemented to support a variety of data bits including 16, 32,128, 256, etc. Similarly, the floating point units 222, 224, can beimplemented to support a range of operands having bits of variouswidths. For one embodiment, the floating point units 222, 224, canoperate on 128 bits wide packed data operands in conjunction with SIMDand multimedia instructions.

In this embodiment, the uops schedulers 202, 204, 206, dispatchdependent operations before the parent load has finished executing. Asuops are speculatively scheduled and executed in processor 200, theprocessor 200 also includes logic to handle memory misses. If a dataload misses in the data cache, there can be dependent operations inflight in the pipeline that have left the scheduler with temporarilyincorrect data. A replay mechanism tracks and re-executes instructionsthat use incorrect data. Only the dependent operations need to bereplayed and the independent ones are allowed to complete. Theschedulers and replay mechanism of one embodiment of a processor arealso designed to catch instruction sequences for sign and absolute valueoperations.

The term “registers” is used herein to refer to the on-board processorstorage locations that are used as part of macro-instructions toidentify operands. In other words, the registers referred to herein arethose that are visible from the outside of the processor (from aprogrammer's perspective). However, the registers of an embodimentshould not be limited in meaning to a particular type of circuit.Rather, a register of an embodiment need only be capable of storing andproviding data, and performing the functions described herein. Theregisters described herein can be implemented by circuitry within aprocessor using any number of different techniques, such as dedicatedphysical registers, dynamically allocated physical registers usingregister renaming, combinations of dedicated and dynamically allocatedphysical registers, etc. In one embodiment, integer registers storethirty-two bit integer data. A register file of one embodiment alsocontains eight multimedia SIMD registers for packed data. For thediscussions below, the registers are understood to be data registersdesigned to hold packed data, such as 64 bits wide MMX™ registers (alsoreferred to as ‘mm’ registers in some instances) in microprocessorsenabled with MMX technology from Intel Corporation of Santa Clara,Calif. These MMX registers, available in both integer and floating pointforms, can operated with packed data elements that accompany SIMD andSSE instructions. Similarly, 128 bits wide XMM registers relating toSSE2 technology can also be used to hold such packed data operands. Inthis embodiment, in storing packed data and integer data, the registersdo not need to differentiate between the two data types.

In the examples of the following figures, a number of data operands aredescribed. FIG. 3A illustrates various packed data type representationsin multimedia registers according to one embodiment of the presentinvention. FIG. 3A illustrates data types for a packed byte 310, apacked word 320, and a packed doubleword (dword) 330 for 128 bits wideoperands. The packed byte format 310 of this example is 128 bits longand contains sixteen packed byte data elements. A byte is defined hereas 8 bits of data. Information for each byte data element is stored inbit 7 through bit 0 for byte 0, bit 15 through bit 8 for byte 1, bit 23through bit 16 for byte 2, and finally bit 120 through bit 127 for byte15. Thus, all available bits are used in the register. This storagearrangement increases the storage efficiency of the processor. As well,with sixteen data elements accessed, one operation can now be performedon sixteen data elements in parallel.

Generally, a data element is an individual piece of data that is storedin a single register or memory location with other data elements of thesame length. In packed data sequences relating to SSE2 technology, thenumber of data elements stored in a XMM register is 128 bits divided bythe length in bits of an individual data element. Similarly, in packeddata sequences relating to MMX and SSE technology, the number of dataelements stored in an MMX register is 64 bits divided by the length inbits of an individual data element. Although the data types illustratedin FIG. 3A are 128 bit long, embodiments of the present invention canalso operate with 64 bit wide or other sized operands. The packed wordformat 320 of this example is 128 bits long and contains eight packedword data elements. Each packed word contains sixteen bits ofinformation. The packed doubleword format 330 of FIG. 3A is 128 bitslong and contains four packed doubleword data elements. Each packeddoubleword data element contains thirty two bits of information. Apacked quadword is 128 bits long and contains two packed quad-word dataelements.

FIG. 3B illustrates alternative in-register data storage formats. Eachpacked data can include more than one independent data element. Threepacked data formats are illustrated; packed half 341, packed single 342,and packed double 343. One embodiment of packed half 341, packed single342, and packed double 343 contain fixed-point data elements. For analternative embodiment one or more of packed half 341, packed single342, and packed double 343 may contain floating-point data elements. Onealternative embodiment of packed half 341 is one hundred twenty-eightbits long containing eight 16-bit data elements. One embodiment ofpacked single 342 is one hundred twenty-eight bits long and containsfour 32-bit data elements. One embodiment of packed double 343 is onehundred twenty-eight bits long and contains two 64-bit data elements. Itwill be appreciated that such packed data formats may be furtherextended to other register lengths, for example, to 96-bits, 160-bits,192-bits, 224-bits, 256-bits or more.

FIG. 3C illustrates various signed and unsigned packed data typerepresentations in multimedia registers according to one embodiment ofthe present invention. Unsigned packed byte representation 344illustrates the storage of an unsigned packed byte in a SIMD register.Information for each byte data element is stored in bit seven throughbit zero for byte zero, bit fifteen through bit eight for byte one, bittwenty-three through bit sixteen for byte two, and finally bit onehundred twenty through bit one hundred twenty-seven for byte fifteen.Thus, all available bits are used in the register. This storagearrangement can increase the storage efficiency of the processor. Aswell, with sixteen data elements accessed, one operation can now beperformed on sixteen data elements in a parallel fashion. Signed packedbyte representation 345 illustrates the storage of a signed packed byte.Note that the eighth bit of every byte data element is the signindicator. Unsigned packed word representation 346 illustrates how wordseven through word zero are stored in a SIMD register. Signed packedword representation 347 is similar to the unsigned packed wordin-register representation 346. Note that the sixteenth bit of each worddata element is the sign indicator. Unsigned packed doublewordrepresentation 348 shows how doubleword data elements are stored. Signedpacked doubleword representation 349 is similar to unsigned packeddoubleword in-register representation 348. Note that the necessary signbit is the thirty-second bit of each doubleword data element.

FIG. 3D is a depiction of one embodiment of an operation encoding(opcode) format 360, having thirty-two or more bits, and register/memoryoperand addressing modes corresponding with a type of opcode formatdescribed in the “IA-32 Intel Architecture Software Developer's ManualVolume 2: Instruction Set Reference,” which is which is available fromIntel Corporation, Santa Clara, Calif. on the world-wide-web (www) atintel.com/design/litcentr. The type of sign operation that multiplies,may be encoded by one or more of fields 361 and 362. Up to two operandlocations per instruction may be identified, including up to two sourceoperand identifiers 364 and 365. For one embodiment of the signinstruction, destination operand identifier 366 is the same as sourceoperand identifier 364. For an alternative embodiment, destinationoperand identifier 366 is the same as source operand identifier 365.Therefore, for embodiments of a sign operation that multiplies, one ofthe source operands identified by source operand identifiers 364 and 365is overwritten by the results of the sign operations. For one embodimentof the sign instruction, operand identifiers 364 and 365 may be used toidentify 64-bit source and destination operands.

FIG. 3E is a depiction of another alternative operation encoding(opcode) format 370, having forty or more bits. Opcode format 370corresponds with opcode format 360 and comprises an optional prefix byte378. The type of sign operation that multiplies, may be encoded by oneor more of fields 378, 371, and 372. Up to two operand locations perinstruction may be identified by source operand identifiers 374 and 375and by prefix byte 378. For one embodiment of the sign instruction,prefix byte 378 may be used to identify 128-bit source and destinationoperands. For one embodiment of the sign instruction, destinationoperand identifier 376 is the same as source operand identifier 374. Foran alternative embodiment, destination operand identifier 376 is thesame as source operand identifier 375. Therefore, for embodiments of thesign operations that multiply, one of the source operands identified bysource operand identifiers 374 and 375 is overwritten by the results ofthe sign operations. Opcode formats 360 and 370 allow register toregister, memory to register, register by memory, register by register,register by immediate, register to memory addressing specified in partby MOD fields 363 and 373 and by optional scale-index-base anddisplacement bytes.

Turning next to FIG. 3F, in some alternative embodiments, 64 bit singleinstruction multiple data (SIMD) arithmetic operations may be performedthrough a coprocessor data processing (CDP) instruction. Operationencoding (opcode) format 380 depicts one such CDP instruction having CDPopcode fields 382 and 389. The type of CDP instruction, for alternativeembodiments of sign or absolute value operations, may be encoded by oneor more of fields 383, 384, 387, and 388. Up to three operand locationsper instruction may be identified, including up to two source operandidentifiers 385 and 390 and one destination operand identifier 386. Oneembodiment of the coprocessor can operate on 8, 16, 32, and 64 bitvalues. For one embodiment, the sign or absolute value operation isperformed on integer data elements. In some embodiments, a sign orabsolute value instruction may be executed conditionally, usingcondition field 381. For some sign or absolute value instructions sourcedata sizes may be encoded by field 383. In some embodiments of a sign orabsolute value instruction, Zero (Z), negative (N), carry (C), andoverflow (V) detection can be done on SIMD fields. For someinstructions, the type of saturation may be encoded by field 384.

FIG. 4 is a block diagram of one embodiment of logic to perform a signoperation on packed data operands in accordance with the presentinvention. Embodiments of the present invention can be implemented tofunction with various types of operands such as those described above.For one implementation, sign operations in accordance to the presentinvention are implemented as a set of instructions to operate onspecific data types. For instance, a packed sign bytes (PSIGNB)instruction is provided to determine the sign for byte data types. Apacked sign words (PSIGNW) instruction is to cause sign operations onword data types. A packed sign doublewords (PSIGND) instruction is toperform sign operations that multiply on doubleword data types. Althoughthese instructions have different names, the general sign operation thatmultiplies performs in a similar fashion. For simplicity, the followingdiscussions and examples below are in the context of a packed sign(PSIGN) instruction to process data elements.

The PSIGN instruction for a sign operation that multiplies of thisembodiment begins with two pieces of information: a first data operandDATA A 410 and a second data operand DATA B 420. For the followingdiscussions, DATA A, DATA B, and RESULTANT are generally referred to asoperands or data blocks, but not restricted as such, and also includeregisters, register files, and memory locations. In one embodiment, eachsign instruction (PSIGNB, PSIGNW, PSIGND) is decoded into onemicro-operation. In an alternative embodiment, each instruction may bedecoded into a various number of micro-ops to perform the sign operationon the data operands. For this example, the operands 410, 420, are 128bit wide pieces of information stored in a source register/memory havingword wide data elements. In one embodiment, the operands 410, 420, areheld in 128 bit long SIMD registers, such as 128 bit SSE2 XMM registers.For one embodiment, the RESULTANT 440 is also a XMM data register.Furthermore, RESULTANT 440 may also be the same register or memorylocation as one of the source operands. Depending on the particularimplementation, the operands and registers can be other lengths such as32, 64, and 256 bits, and have byte, doubleword, or quadword sized dataelements. Although the data elements of this example are word size, thesame concept can be extended to byte and doubleword sized elements.Where the data operands are 64 bit wide, MMX registers are used in placeof the XMM registers.

The first operand 410 in this example is comprised of a set of eightdata elements: A7, A6, A5, A4, A3, A2, A1, and A0. Each individual dataelement corresponds to a data element position in the resultant 440. Thesecond operand 420 is comprised of another set of eight data segments:B7, B6, B5, B4, B3, B2, B1, and B0. The data segments here are of equallength and each comprise of a single word (16 bits) of data. However,data elements and data element positions can possess other granularitiesother than words. If each data element was a byte (8 bits), doubleword(32 bits), or a quadword (64 bits), the 128 bit operands would havesixteen byte wide, four doubleword wide, or two quadword wide dataelements, respectively. Embodiments of the present invention are notrestricted to particular length data operands or data segments, and canbe sized appropriately for each implementation.

The operands 410, 420, can reside either in a register or a memorylocation or a register file or a mix. The data operands 410, 420, aresent to the sign computation logic 430 of an execution unit in theprocessor along with a sign instruction. By the time the signinstruction reaches the execution unit, the instruction should have beendecoded earlier in the processor pipeline. Thus the sign instruction canbe in the form of a micro operation (uop) or some other decoded format.For this embodiment, the two data operands 410, 420, are received atsign computation logic 430. The sign computation logic 430 selects thesign value or signum for each data element of the first operand 410,multiplies that sign value with the value of the data element in thecorresponding data element position of the second operand 420, andplaces the product for that multiplication into the appropriate positionin the resultant 440. Although the general concept of a multiplyoperation is discussed here, other methods and means to achieve the samedesired results as a multiply with a multiplication are possible. Forexample, in one embodiment, multiplication can be performed with amultiplication unit. In another embodiment, the same results can beobtained by logic to process an algorithm to leave a value unchanged,set to zero, or changing a sign from ‘+’ to ‘−’ or vice versa.

This processing of the sign extraction and multiplication is repeatedfor the entire set of data element positions in the first operand 410.Although the data processing of this embodiment is comprised of the signextraction and multiplication, the terms ‘sign operation’ or ‘signoperation that multiplies’ may also be used generally here to referencethis data processing. For one embodiment, the data elements for all ofthe data positions are processed in parallel. In another embodiment, acertain portion of the data element positions can be processed togetherat a time. Here, the resultant 440 is comprised of eight products:B7×SIGN_(A7), B6×SIGN_(A6), B5×SIGN_(A5), B4×SIGN_(A4), B3×SIGN_(A3),B2×SIGN_(A2), B1×SIGN_(A1), and B0×SIGN_(A0). For this embodiment, thesignum or sign value (SIGN_(X)) for a data element is a ‘+1’ for apositive non-zero number, a ‘−1’ for a negative non-zero number, and a‘0’ for a zero. In one alternative embodiment where the architectureallows for a ‘+0’ and a ‘-0’, both types of zeroes are treated as azero, wherein the signum or sign value of the data element is a ‘0’.

FIG. 5 illustrates the operation of a sign operation that multiplies ondata elements in accordance with one embodiment of the presentinvention. The sign operation of this example can occur within the signcomputation logic 430 of FIG. 4. In this example, the sign operation 530is described with the data elements for a single data element position.A first data element, DATA ELEMENT A 510, from a first data operand anda second data element, DATA ELEMENT B 520, from a second data operandare brought together. Each data element is comprised of a value having asign portion and a numeric value base portion. For example, DATA ELEMENTA 510 is interpreted as a number 512 comprised of SIGN_(A) and BASE_(A).Similarly, DATA ELEMENT B 520 is interpreted as a number 522 comprisedof SIGN_(B) and BASE_(B).

During the sign operation 530, the sign computation logic takes the signvalue of the first operand, SIGN_(A) for DATA ELEMENT A 510, andmultiplies that sign value with the number in DATA ELEMENT B 520. In oneinstance, the logic is to perform the appropriate multiplicationoperation in response to the value of SIGN_(A). The sign portion for anumber can be negative ‘−’ or positive ‘+’. The value portion of anumber can be a zero ‘0’ or a non-zero value. For the sign operation ofone embodiment, the logic bins the first data element into one of threecategories: positive ‘+’, zero ‘0’, or negative ‘−’. If the first dataelement 510 is positive, meaning its sign is positive, then the result540 for that data position is essentially the second data element 520itself, as a positive sign is treated as a multiply of the second dataelement 520 by a SIGN_(A) equal to ‘+1’. If the first data element 510is zero, the sign value of the first data element 510 is disregarded asthe zero is essentially calling for a multiply of the second dataelement 520 by a SIGN_(A) equal to zero, which yields a result 540 ofzero. If the first data element 510 is negative, meaning its sign isnegative, then the result 540 for that data position is going to be theproduct of the multiplication of the second data element 520 by aSIGN_(A) equal to ‘−1’. The result 540 of the sign operation thatmultiplies for a given data element position involving DATA ELEMENT A510 and DATA ELEMENT B 520 is ‘SIGN_(A)×DATA ELEMENT_(B)’. In anotherembodiment, the logic may be able to multiply the sign values, SIGN_(A)and SIGN_(B), together and apply the resultant sign value to BASE_(B) toform the final result for that data element position.

FIG. 6A is a block diagram of one embodiment of a circuit 600 forperforming a sign operation that multiplies in accordance with thepresent invention. The circuit 600 of this embodiment comprises amultiplexing structure and logic to evaluate the sign value of anelement from the first source operand and to effectively calculate theproduct of that sign value with a corresponding element from the secondsource operand. The circuit 600 in FIG. 6A is shown for one data elementposition or slice of the resultant packed data block for simplifying thediscussion. Furthermore, the logic 600 as shown for this data elementposition can exist in multiple instantiations on the same executionunit. Depending on the particular implementation, a number of thecircuit elements are extrapolated out as needed for the desired numberof data elements. For example, with eight data elements, enoughmultiplexers and adders to handle all the bits of the eight dataelements may be physically present. Similarly, there can be sixteeninstantiations of the circuitry to handle two operands having sixteendata element each. In another embodiment, some of the logic like theadder 614, for instance, may shared among all the data elementpositions. In yet another implementation, the circuitry is capable ofprocessing packed data and data for multiple data element positions canbe processed through the logic together.

For this embodiment, a portion of the logic for the sign operation alsoshared with other packed operations in order to reduce the device countand redundancy. The circuit 600 of this embodiment receives input dataelements from source operands and outputs a resultant data element for aparticular data element position in a resultant packed data operand.Although the source elements, SRC X 602 and SRC Y 604, are referred toas single data elements here, it is understood that these elements arepart of larger packed data operands that are accompany a packed signinstruction. In this embodiment, the first source data element, SRC X602, is coupled to a two input (2:1) multiplexer (mux) 606. A SIGNsignal 622 controls the operation of that 2:1 mux. For this embodiment,if a sign operation is being serviced, SIGN 622 causes the mux 606 tooutput the ‘0’ that is coupled as the second input to the mux 606. Ifanother type of operation is being performed, SIGN 622 causes the mux606 to output SRC X 602.

The second source data element, SRC Y 604, of this embodiment, iscoupled to another 2:1 mux 608 as inverted 605 and non-inverted 604versions. If a sign operation is being performed, SIGN 622 causes themux 608 to output the inverted input 605. In this example, the invertedversion 605 of SRC Y 604 can be used to achieve a subtraction. The twomuxes 606, 608, are coupled to an adder 614. The mux outputs 610, 612,are first and second inputs, respectively, to adder 614. Adder 614 is toadd together its inputs to generate a sum at its output 616. During asign operation, the adder receives ‘0’ as its first input 610 and theinverted SRC Y 605 as its second input 612. The adder 614 appears to addthe inverted SRC Y 605 to ‘0’ 603. But the inversion of SRC Y 604 ofthis embodiment basically causes SRC Y 604 to change sign from positiveto negative or from negative to positive. Thus, the inverted SRC Y 605is essentially causing the adder 614 to mathematically subtract SRC Y604 from ‘0’ 603. The output 616 of adder 614 can be represented as thesum of ‘0−SRC Y’.

The data bits of SRC X 602 are also coupled to a zero detector circuit624, which is to detect if SRC X 602 is equal to a zero value. The zerodetector output 626 that indicates if an overall zero value is detectedis coupled as a control signal to a three input (3:1) mux 618 and as aninput to a logical NOR gate 628. The zero detection of one embodiment isperformed in parallel with the addition and does not create any newcritical timing paths. The N sign bits 620 of SRC X 602, N being anumber of one or greater, are also coupled to the logical NOR gate 628and as a control to the 3:1 mux 618. This NOR gate 628 is to output anactive high signal if both of its inputs are active low. In thisexample, the NOR gate output 632 will be high if both the input of signbits 620 is low, indicating that SRC X 602 is positive, and the input ofthe zero detectors result is low, indicating that SRC X 602 is anon-zero value.

The group of control signals 634 coupled to the 3:1 mux 618 operate toselect the appropriate data value to output as resultant 630. Datavalues of SRC X 602, SRC Y 604, and the sum of ‘0−SRC Y’ 616 are coupledas inputs to the 3:1 mux 618. For this embodiment, the signals 634 areto cause one of the inputs to be selected in accordance to one of threesituations. The first case arises if the first source element SRC X 602is a zero. In other words, the second data element 604 is to bemultiplied by zero. This condition is indicated with the zero detectoroutput 626. In this situation, the input of SRC X 602, which is a zerovalue here, is selected and outputted as resultant 630. In thisembodiment, this zero condition the other control signals 620, 632, aretrumped and a zero is outputted regardless of the sign value of SRC X602 and the contents of SRC Y 604.

The second case arises if the first source element SRC X 602 is positiveand a non-zero value. This condition is indicated with the NOR gateoutput 632. Essentially, the second data element 604 is to be multipliedby ‘+1’, which will yield SRC Y 604 itself. In this case, the input ofSRC Y 604 is selected and outputted as resultant 630. The third casearises if the first source element SRC X 602 is negative and a non-zerovalue. This situation is indicated with the N sign bits 620 of SRC X602, which provide an active high value if SRC X 602 is negative and anactive low value if SRC X 602 is positive. In this case, the input ofthe sum for ‘0−SRC Y’ 616 is selected and outputted as resultant 630.Essentially, the negative sign of SRC X 602 is treated as a ‘−1’ and the‘0−SRC Y’ calculation is mathematically equivalent to a multiplicationof the second data element SRC Y 604 by a factor of ‘−1’. For thisembodiment, the resultants for this and the other data element positionsare packed together into a resultant data block having the same size asthe source data operands. For example, if the source packed dataoperands are 64 or 128 bit wide, the resultant packed data block is also64 or 128 bit wide, respectively. Furthermore, the source data operandsfor a sign operation can come from a register or a memory location. Forthis embodiment, the resultant packed data block overwrites the data inthe SIMD register for one of the source data operands.

FIG. 6B is a block diagram of another embodiment of a circuit 650 forperforming a sign operation in accordance with the present invention.While the circuit arrangement and connections are different, the generalscheme and functionality of this embodiment is similar to that of thecircuit 600 in FIG. 6A. The circuit 650 of this embodiment also includesa multiplexing structure and logic to evaluate the sign of a first dataelement and to multiply that sign with a second data element. Thiscircuit 650 is shown and described in the context of a single dataelement position or slice of the resultant packed operand, but theapparatus and methodology can be extended as needed and applied tovarious length operands based on the particular implementation. Thus,certain circuit elements of FIG. 6B can be replicated in order to servemore data elements. For example, if the operands are capable ofincluding sixteen data element positions, the circuitry of FIG. 6B canbe expanded to support the sixteen data element positions.

The circuit 650 of this embodiment receives input data as a first dataelement SRC X 602 from a first packed operand and a second data elementSRC Y 604 from a second packed operand. SRC X 602 is coupled to as aninput to a 3:1 mux 618 and to zero detector logic 624. The zero detector624 is to determine whether SRC X 602 is a zero. SRC Y 604 is coupled tothe 3:1 mux 618 and an inverted version 613 (−SRC Y) is coupled to anadder 614. The adder 614 is to add the inverted SRC Y 613 to the otheradder input, ‘0’ 603 in this case, to obtain a sum at its output 616. Byadding an inverted version of SRC Y 604, the adder is adding zero withnegative SRC Y, or mathematically subtracting SRC Y from ‘0’. The output616 for the adder 614 is ‘0−SRC Y’ and is coupled as an input to the 3;1mux 618. The value ‘0−SRC Y’ is also equivalent to multiplying SRC Y 604by ‘−1’.

The output signal 626 of the zero detector circuit 624 is coupled as acontrol signal to the 3:1 mux 618 and also as an input to a two inputlogical NOR gate 628. Similarly, the N sign bits 620 of SRC X 602 arecoupled to the 3:1 618 as a control and as the other input to the NORgate 628. The output 632 of the NOR gate 628 for this embodiment isactive high if the sign bits 620 and the zero detector output 626 areboth active low. The NOR gate output 632 is also coupled to the 3:1 mux618 as a control signal. This set of control signals 634 is to selectone of the three mux inputs 602, 604, 616, to output as the resultant630 depending on which of the conditions exists. The three situations,as described above for FIG. 6A, are: (1) SRC X 602 is a zero; (2) SRC X602 is positive and a non-zero value; and (3) SRC X 602 is negative anda non-zero value. For the first case, SRC X 602, which will be a zero,is selected. In the second case, SRC Y 604, which is equal to ‘SRC Yx+1’, is selected. For the third case, ‘0−SRC Y’ 616, which is equal to‘SRC Y x−1’ is selected. The resultant for each data element position ispacked together with others into a resultant data operand.

FIG. 7 illustrates the operation of a packed sign instruction on aplurality data elements in accordance with one embodiment of the presentinvention. This is an example of the instruction “PSIGNW DATA B, DATAA”. The PSIGNW instruction is to cause a sign operation that multipliesto operate on word size data elements in the first source packed operandDATA B 711 and the second source packed operand DATA A 701. Thedescription here is also applicable to other packed sign instructionslike PSIGNB and PSIGND. In this example, the signs from one source data701 are applied to the values of another source data 711 viamultiplication to obtain a product that is organized into a destinationdata storage device 721. The two source operands, DATA A 701 and DATA B711, are each comprised of eight packed data elements in this example,as does the resultant 721. In this embodiment, each of the data elementsinvolved is eight bits or a byte wide. Thus, DATA A 701, DATA B 711, andRESULTANT 721 data blocks are each 128 bits long. Furthermore, thesedata blocks can reside in memory and/or registers.

As shown in FIG. 7, DATA A 702 includes data elements with numericvalues in base 10 of: ‘−4270’ 702, ‘240’ 703, ‘−3573’ 704, ‘7033’ 705,‘−2427’ 706, ‘−9703’ 707, ‘0’ 708, ‘2605’ 709. Similarly, DATA B 711includes source data elements with base 10 values of: ‘−1120’ 712,‘6401’ 713, ‘36’ 714, ‘0’ 715, ‘691’ 716, ‘−6780’ 717, ‘−855’ 718,‘5177’ 719. The base 10 numbers are further noted below with a subscript₁₀ suffix. Accordingly, the sign for each data element in the seconddata operand 701 is extracted and multiplied with the number for eachdata element in the corresponding data element position in the firstdata operand 711. If a number is ‘0’ for a data element in the secondoperand 701, a ‘0’ is also entered in the corresponding resultant dataelement position. For one embodiment, the processing of a sign operationthat multiplies for one or more data element positions in the sourcedata 701, 711, can be perform in parallel.

As the sign value for each of the data elements in the second operand701 are evaluated, the number in the corresponding data element positionin the first operand 711 is multiplied by appropriate factor. For thisembodiment, the multiplicand is either ‘−1’, ‘0’, or ‘+1’, depending onthe sign value of the second operand data element. Although the signoperation is described here with multiplication, an actualmultiplication operation may not be physically necessary to arrive atthe same mathematical result. For instance, it is unnecessary to do amultiplication with ‘0’ to arrive at a product of ‘0’. Nor is itphysically necessary to multiply a number by ‘+1’ as the product will bethe number itself. Similarly, the result of a multiplication of a numberby ‘−1’ can also be achieved by subtracting the number from ‘0’.

For instance, the left most data element 702 of the second operand 701has a value of ‘-4270₁₀’, which is a negative number. Meanwhile, theleft most data element 712 of the first operand 711 contains a value of‘-1120₁₀’. Because the sign value of the second operand data element 702is negative, the value ‘-1120₁₀’ of the corresponding first operand dataelement 712 is conceptually multiplied by ‘−1’ to yield a product of‘1120₁₀’ during the packed sign operation. The product is stored intothe appropriate data element position 722 of the resultant 721.

Similarly, the right most data element 709 of the second operand 701 hasa value of ‘2605₁₀’, which is a positive number. Meanwhile, the rightmost data element 719 of the first operand 711 contains a value of‘5177₁₀’. Because the sign value of the second operand data element 709is positive, the value ‘5177₁₀’ of the corresponding first operand dataelement 719 is conceptually multiplied by ‘+1’ to yield a product of‘5177₁₀’ during the packed sign operation. The product is stored intothe right most data element position 729 of the resultant 721. Giventhat the sign value of the second operand data element 709 is positivehere, an actual multiplication would not be needed as the product 729 issimply the value of the first operand data element 719.

At the second data element 708 from the right in the second operand 701,the value is ‘0₁₀’. Meanwhile, the second data element 718 from theright in the first operand 711 contains a value of ‘−855₁₀’. Because thenumber of the second operand data element 708 is zero, the value‘−855₁₀’ of the corresponding data element 718 is basically beingmultiplies by ‘0’ to yield a product of ‘0’ during the packed signoperation. Thus, a ‘0’ is stored into the second data element position728 from the right in the resultant 721. Because the second operand dataelement 708 has a zero value, a multiplication is unnecessary to realizethe product will be ‘0’. Similarly, a zero value in a second operanddata element is defined in this embodiment to cause a ‘0’ in theresultant position regardless of any sign value that may exist for thesecond operand data element.

FIG. 8A is a flow chart 800 illustrating one embodiment of a method toperform a sign operation. The length value of L is used here torepresent the width of the operands and data blocks. Depending on theparticular embodiment, L can be used to designate the width in terms ofnumber of bits, bytes, words, etc. Similarly, the term M is used todesignate the number of data elements or segments packed within anoperand. At block 810, a first length L data operand B having M elementsis received. A second length L data operand A also having M elements isreceived at block 820. For this embodiment, the source operands andresultant are of equal length and have the same number of data elements.At block 830, an instruction to perform a sign operation that multipliesis processed.

The details of the sign operation at block 830 of this embodiment arefurther described in terms of what occurs for each data elementposition. For one embodiment, the sign operation for all of the packedresultant data element positions are processed in parallel. In anotherembodiment, a certain portion of the data elements may be processed at atime. At block 831, a check is made to determine whether the value forthe element from data operand A is negative (less than zero). If thevalue is determined to be negative, the resultant value for thisparticular data element position is calculated at block 832 as theproduct of the value for the element from data operand B multiplied by‘−1’. If the value for the element from operand A is not negative atblock 831, a determination is made at block 833 as to whether the valuefor the element from operand A is equal to zero. If the value isdetermined to be zero, the resultant value for this data elementposition is set to ‘0’ at block 834. But if the value for the operand Aelement is not found equal to zero at block 833, yet anotherdetermination is made at block 835 as to whether the value for thisoperand A element is positive (greater than zero). If the value for thisoperand A element is positive, the resultant value for this particulardata element position is calculated at block 836 as the product of thevalue for the operand B data element multiplied by ‘+1’. If the value ofthe operand A element is not positive at block 835 for this embodiment,the value is treated as undefined at block 837 as none of the threesituations (positive, ‘0’, negative) apply. These resultant values forthese different data elements are arranged into the appropriate dataelement positions corresponding to the source element pairs in theresultant packed operand.

FIG. 8B is a flow chart 850 illustrating another embodiment of a methodto perform a sign operation. The flow of the method at block 810 and 820for this embodiment are similar to that of FIG. 8A. In this example, themethodology for block 830 in performing a sign operation that multipliesis somewhat different. The details of the sign operation at block 830for this embodiment are also further described in terms of what occursfor each data element position. At block 840, a determination is made asto whether the value in the element of data operand A is equal to zero.If the determination is true and the value is zero, a ‘0’ is entered asthe resultant value for this data element position at block 841. But ifthe determination is that the operand A data element for this positionis a non-zero value, the resultant value for this data element positionis calculated at block 842 as the product of the value for the operand Bdata element multiplied by the sign of the operand A data element. As inFIG. 8A, the resultant value for each of the data element positions arearranged into the appropriate place in the resultant packed data block.

FIG. 9 is a block diagram of one embodiment of logic to perform anabsolute value operation on a packed data operand. For one embodiment,absolute value operations in accordance to the present invention areimplemented as a packed absolute (PABS) instruction to operate onvarious sized data types. For simplicity, this PABS instruction isdescribed here in general terms with a packed operand having eight dataelements. These data elements can be bytes, words, doublewords, etc.depending on the particular implementation. In this example, the packedabsolute operation is invoked with a line of code like “PABS SRC1”,wherein SRC1 points to a SIMD register or a memory location. In thiscase, SRC1 is both the data source and result destination. For oneembodiment, the instruction format requires two operands and the linewould read “PABS SRC1, SRC2”. In that this case, the PABS instructioncauses the absolute value in data elements of SRC2 to be placed intoSRC1. Furthermore, in one embodiment, a packed absolute bytes (PABSB)instruction is provided to generate absolute values of byte data types;a packed absolute words (PABSW) instruction is provided to generateabsolute values of word data types; and a packed absolute doublewords(PABSD) instruction is provided to generate absolute values ofdoubleword data types.

The PABS instruction for an absolute value operation of this embodimentbegins with a first data operand SOURCE DATA 910 having eight dataelements: A7, A6, A5, A4, A3, A2, A1, and A0. Each individual dataelement corresponds to a data element position in the resultant 930. Thedata operand 910 is sent to absolute value computation logic 920 alongwith a absolute value instruction. The absolute value computation logic920 modifies the value in each source data element so that the numericvalue in the corresponding element position in the resultant 930 willhave the unsigned absolute value of that source data element number. Forexample, the left most resultant element position has the unsignedabsolute value of the number of source element A7. This processing ofthe absolute value is repeated for the entire set of data elementpositions in the source operand 910. For this embodiment, the resultantlocation can be the same as the source operand location. In analternative embodiment where two operands are specified with the PABSinstruction, one operand can specify the source and the other canspecify the destination.

Compression is frequently implemented in image processing. Video framesare generally compressed in blocks of pixels. Highly compressed videocan exhibit blocking artifacts due to the quantization operation. Inmany coding algorithms, one type of image deterioration that occurs atlower bit rates is called a blocking effect. This effect is caused bythe unnatural way of dividing up images into rectangular blocks with afixed grid during image processing. Because the coding of each block isindependent, nothing assures the continuity of the coded image values atthe border between blocks. Quantization of the DC coefficient of thediscrete cosine transform can add or subtract an offset to a blockcausing it to become brighter or darker than adjacent blocks andcreating the appearance of lines along block boundaries. This cansometimes give rise to prominent artificial edges and blocking artifactsin the coded image. In image sequences, a background grid of non-movingedges viewed against a moving scene can result in a very unnatural andunpleasant type of degradation. In order to prevent these blockingeffects from occurring, a deblocking scheme can be use filters to smoothout the artificial edges. These artifacts can be made less noticeablewith a deblocking algorithm that smoothes the boundary between blocks.However, the algorithm should not smooth a step between blocks if thereis a true edge along the block boundary. Generally the step betweenadjacent blocks is considered a true edge if the size of the edge stepis greater than the step size that could be created by quantization.Similarly, other algorithms can be use to fit surfaces over a block.

Some of the deblocking algorithms for the video compression methodsH.263 and MEPG4 use a sign or signum operation and a absolute valueoperation. In these video deblocking algorithms, the sign functioncomputes the sign of the correction factor. The absolute value operationis used to determine the magnitude of the correction factor and comparevariations in the video with predetermined thresholds. Embodiments ofSIMD instructions like the PSIGN and PABS as described earlier can beused together in deblocking algorithms for H.263 and MPEG4. The signumoperation involves evaluating the sign value from a data and providingan indication of what is the sign value. For instance, a signumoperation on a data element will output a ‘0’ if the data element iszero, a ‘−1’ if the data element is negative, and a ‘+1’ if the dataelement is positive. For one embodiment, the PSIGN instruction inaccordance to the present invention can be used to provide the signumfunctionality.

One approach to nonlinear filter deblocking employs a three stepnonlinear filtering approach. First, characterize the block boundary.Second, use the results of the first step to compute factors to correctvalues of pixels along the block border. And third, correct pixel valuesof pixels along the border by adding or subtracting factors computed inthe second step. The following example describes the H.263 deblockingalgorithm of one implementation. A and B are pixels on one side of ablock boundary. A 1012 is an array of pixels one pixel distance awayfrom a block boundary. B 1014 is an array of pixels along the blockboundary. C and D are pixels on the other side of the boundary. C 1022is an array along the block boundary on the other side of the boundaryfrom array B. D 1024 is an array of pixels one pixel distance from theblock boundary in the same block 1020 as array C 1022. In order toreduce a continuity artifact due to quantization between block X 1010and block Y 1020, but preserving a real edge, deblocking is performed.The deblocking results are labeled as A′, B′, C′, and D′.

FIG. 10 illustrates the operation of a deblocking algorithm using SIMDinstructions in accordance with the present invention. Two blocks ofdata 1010, 1020, are shown in FIG. 10. In this example, the blockscontain data for an image or video stream. Each block is comprised of aplurality of rows and columns of data elements. For example, a block insome image processing algorithms is a eight by eight block of data.Here, the illustration is focused on the block boundary between BLOCK X1010 and BLOCK Y 1020. The bottom two data rows 1012, 1014, are shownfor BLOCK X 1010. BLOCK Y 1020 is shown with the top two data rows 1022,1024. Each data row is comprised of data elements numbered from 7through 0.

SIMD registers are loaded with the pixel data for arrays A 1012, B 1014,C 1022, and D 1024. First, the block boundary is characterized. The sizeand direction of the step across the block boundary is determined. Thiscan be represented by the equation:

d=(A−4B+4C−D)/8.

Then, correction factor for arrays B 1014 and C 1022 are calculated withan updown ramp:

d ₁=SIGN(d)×(MAX(0,ABS(d)−MAX(0,2×(ABS(d)−strength)))).

The correction factor for arrays A 1012 and D 1024 are calculated:

d ₂=clipd1((A−D)/4,d ₁/2).

Here, the absolute value and maximum and clipping operations are used tocompute the magnitude of pixel correction factors d₁ and d₂. The signoperation also uses the factor d from the first step to compute the signof the correction factor d₁. Correction factors d₁ and d₂ are eitheradded or subtracted from the pixel values. The boundary pixels forarrays B 1014 and C 1022 are corrected:

B′=clip(B+d ₁); and C′=clip(C−d ₁).

The pixels for arrays A 1012 and D 1024 are then corrected:

A′=A−d2;D′=D+d ₂.

The d₁ calculation is a function called a updown ramp. The peak value iswhen d is equal to ‘strength’ and the value goes to zero when d is equalto ‘2×strength’. The value of ‘strength’ is determined by thequantization step size. Generally, ‘strength’ is about half the stepsize. The function ‘clipd1( )’ clips the result of ‘(A−D)/4’ to + or −the absolute value of ‘d₁/2’. The function ‘clip( )’ clips the evaluatedresult to a value of ‘0’ or ‘255’. Embodiments of this algorithm can beimplemented with SIMD instructions. For this embodiment, the signoperation can be implemented with a PSIGNB or PSIGNW instruction.Similarly, the absolute value operation can be implemented with PABSB orPABSW. In this embodiment, multiple pixel values for arrays A, B, C andD are loaded into separate SIMD registers. For one embodiment, thedeblocking operations are applied to more than one pixel column at atime or in parallel. Multiple values of intermediate values d₁ and d₂are computed in separate SIMD registers using sign, absolute value, andmaximum instructions. The results A′, B′, C′, and D′ are computed inseparate SIMD registers. Clipping operations can be computed with SIMDmaximum and minimum instructions.

The functionality of a sign instruction as described above is used inthe nonlinear filtering deblocking algorithm of this embodiment.Embodiments of this deblocking algorithm can be implemented with codingtechniques like those of H.263 or MPEG4 to remove blocking artifactscaused by the quantization operation of these two common videocompression methods. By using a sign instruction that multiplies in adeblocking algorithm, embodiments of the present scheme can speed upcalculations for these coding algorithms and reduce code size. Forexample, a single PSIGN instruction can replace the multiple arithmeticinstructions that have been needed to perform similar data manipulationor instructions that cannot operate on packed data. Thus the overallthroughput can be improved and processing resources freed up.

For one embodiment of a deblocking algorithm, the sign instruction andthe absolute value instruction do not have saturation behavior. Thismeans that for a packed absolute value instruction, an N bit data with avalue −2^(n-1) will be evaluated to 2^(n-1). In the case of a packedsign instruction, an N bit data with a first source element equal to−2^(n-1) and a negative second source element will be evaluated to2^(n-1). In some cases, signed results are needed, so no positive valuegreater than 2^(n-1)−1 is permitted. One solution is to force themaximum negative and positive values to have the same magnitude beforethe PABS or PSIGN instructions are executed.

The sign and absolute value operations of one embodiment can also beapplied to an MPEG4 deblocking algorithm as described below. Ten pixels,five n either side of a block boundary, is represented as: V0 V1 V2 V3V4|V5 V6 V7 V8 V9. The ‘|’ represents the block boundary. First theblock boundary is characterized:

count=φ(V0−V1)+φ(V1−V2)+φ(V2−V3)+φ(V3−V4)+φ(V4−V5)+φ(V5−V6)+φ(V6−V7)+φ(V7−V8)+φ(V8−V9),

wherein φ(γ)=1 if the ABS(γ)<=THRESHOLD1, else φ(γ)=0.If count is greater than or equal to THRESHOLD2, use a DC mode, else usedefault mode.The block boundary is also DC characterized:

max value=MAX(V1,V2,V3,V4,V5,V6,V7,V8);

min value=MIN(V1,V2,V3,V4,V5,V6,V7,V8).

If (ABS(max value−min value)<2×a quantization factor) then the DCrelated correction steps 2 and 3 are done, otherwise no correction ismade. For the default mode, the correction factor is calculated as:

a3,0=(2×V3−5×V4+5×V5−2×V6)/8;

a3,1=(2×V1−5×V2+5×V3−2×V4)/8;

a3,2=(2×V5−5×V6+5×V7−2×V8)/8;

a3,0′=SIGN(a3,0)×MIN(ABS(a3,0),ABS(a3,1),ABS(a3,2));

d=CLIP(5×(a3,0′−a3,0)/8,0,((V4−V5)/2)×δ(ABS(a3,0)<a quantizationfactor)),

wherein δ( ) evaluates to 1 if true and 0 if false.

The boundary pixels are then corrected. The function CLIP(r, p, q) clipsr between p and q. For the DC mode, the correction factor is calculatedas:

if m<1, then if ABS(V1−V0)<QP, then p _(m) =V0; else p _(m) =V1;

if 1<=m<=8, then p _(m) =V _(m);

if m>8, then if ABS(V8−V9)<a quantization factor, then p _(m) =V9, elsep _(m) =V8.

FIG. 11 is a flow chart 1100 illustrating one embodiment of a method toperform a deblocking algorithm using SIMD instructions. For example,such a deblocking algorithm can be implemented with code for H.263 andMPEG4 compression methods. At block 1102, pixel data for a first blockand a second block is received. The block boundary between the twoblocks are characterized at block 1140. One or more correction factorsare computed on the packed pixel data at block 1106 through the use ofinstructions for packed sign operations that multiply and packedabsolute value operations. The use of a PSIGN and/or PABS instructionswhen computing correction factors for a deblocking algorithm can reducethe number of non-SIMD instructions needed and increase the efficiencyof processing resources. For example, one embodiment of a deblockingsequence for image processing algorithms in accordance to the presentinvention employs a PSIGN operation to determine the sign of thecorrection factor and PABS is used to calculate the magnitude of thecorrection factor. At block 1108, the boundary pixels for the firstblock and the second block are corrected with one or more of thecorrection factors that were calculated with a sign operation thatmultiplies or an absolute value operation.

Thus, techniques for nonlinear filtering and deblocking applicationsutilizing SIMD sign and absolute value operations are disclosed. Whilecertain exemplary embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative of and not restrictive on the broad invention, andthat this invention not be limited to the specific constructions andarrangements shown and described, since various other modifications mayoccur to those ordinarily skilled in the art upon studying thisdisclosure. In an area of technology such as this, where growth is fastand further advancements are not easily foreseen, the disclosedembodiments may be readily modifiable in arrangement and detail asfacilitated by enabling technological advancements without departingfrom the principles of the present disclosure or the scope of theaccompanying claims.

What is claimed is:
 1. A processor comprising: a plurality of packeddata registers; a decoder to decode an instruction, the instruction toindicate a first source packed data that is to be stored in theplurality of packed data registers and that is to have a first pluralityof packed data elements, to indicate a second source packed data that isto be stored in the plurality of packed data registers and that is tohave a second plurality of packed data elements, each of the dataelements of the first source packed data to correspond to a differentone of the data elements of the second source packed data in acorresponding position; and an execution unit coupled with the decoderand the plurality of packed data registers, the execution unit inresponse to the instruction, to store a packed data result in adestination packed data register of the plurality of packed dataregisters, the packed data result to include a plurality of result dataelements, each of the result data elements to correspond to a differentone of the data elements of the first source packed data in acorresponding position, and to correspond to a different one of the dataelements of the second source packed data in a corresponding position,wherein: result data elements that correspond to positive data elementsof the second source packed data are to store values of thecorresponding data elements of the first source packed data; and resultdata elements that correspond to negative data elements of the secondsource packed data are to store negated values of the corresponding dataelements of the first source packed data.